Table 2. Dextran penetration (µm) in FIXED fibers.

Calculated and measured dextran penetration in fixed fibers. The expected tracer penetration through different pathways in a fiber was calculated as in Table 1. Here too, average measured penetration at all time points approximates calculated penetration through pathway 3, but differs from that through pathways 1 and 2 by ~ two orders of magnitude. For comparison with live fibers, diffusion for corresponding time points has been estimated from the measured values. n, number of paranodes measured.

		Pathways
Tracer	Time (min)	1	2	3
		Calculated			Measured	n	Estimated
3K	30	440	409	2.8	2.2 ± 1.4	15
	45	540	509	3.4	2.6 ± 1.5	35
	60	621	590	4.0			3.0
	75	650	619	4.1	5.3 ± 2.8	210
70K	135	324	293	2.1	4.4 ± 2.6	207
	150	342	311	2.2			4.6